WatchTower Robotics: Preventing waste water one cracked pipe at a time

Meet the Inventors Week 04 — Every year 20 percent of our global clean drinking water supply is wasted. Now a US-based inventor, Dr You Wu, is attempting to save water using a robot that can pinpoint underground leaks.

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Mar 26 · 5 min read
Dr Wu You’s invention “Lighthouse” won the 2018 National US James Dyson Award | Photography Matthew Beedle

The Problem: Finding a cracked pipe in a city?

It’s like clockwork. Every Thursday morning, the taps run dry at You Wu’s family home.

It’s part of a rotating shut-off system meant to preserve water in Changzhou, a city of 4.5 million in eastern China’s Yangtze river delta. Growing up, Wu understood it to be a measure of conservation to combat water scarcity.

The weekly outages have since taken on a new meaning for Wu, now 29 years old.

“The whole city loses about 30 percent of its water through leaks. It’s just lost,” he says. “The system is losing more water than we actually save.”

This experience sat at the back of Wu’s mind as he moved from Changzhou to Indiana to study mechanical engineering at Purdue University. Later, during his Master’s and PhD at MIT, he joined a research group focused on water leaks. The next logical step for the young engineer had to be trying to build a crack detecting device.

As part of his research into the problem, he soon learned that Changzhou’s leaky pipes aren’t an anomaly. In fact, the world loses 46 billion litres of treated water a day thanks in large part to underground leaks. Lost water — known in the industry as “non-revenue water” because it never reaches the consumer — is a problem that spans all continents, in industrialised and developing cities alike.

Lighthouse shown near a “test tube” | Photography Dyson

It’s the people experiencing drought and water scarcity, however, who feel it first and worst. Last year in Jakarta, residents went days without clean water. The Indonesian city loses 44 percent of its treated water, due mainly to leaks and theft. In Cape Town, South Africa, officials are counting down to Day Zero — the increasingly un-theoretical moment when taps would be shut off and residents would have to line up for their daily water rations.

And if global water supplies could get even worse over time due to climate change, fixing leaky pipes seems like an easy solution.

Unfortunately, even this isn’t an easy solution. A city’s underground water-pipe infrastructure can span thousands of kilometres, and existing crack-detection tools haven’t been great at pinpointing a leak’s precise location. “If you don’t know where the crack is, you have to dig up the street,” says Wu.

This work is costly and strains municipal budgets; in Los Angeles, replacing just 20 percent of the city’s ageing water pipes is projected to cost $1 billion. Nationally, repairs and expansion will cost more than $1 trillion. Meanwhile, the American Society of Civil Engineers says it would take the US 200 years to rebuild the pipe network at cities’ average rates of replacement.

Wu says repair costs and timelines easily balloon because of how imprecise the whole process is. “If you knew where [the crack] was, you could fix it in four to six hours. When you don’t know where it is, it can take two or three days, six people digging every night. Those costs can easily go above $200,000,” he says. “If you do it right the first time, it costs maybe $20,000.”

So, how can cities do it right the first time?

Wu believes he’s found the way with Lighthouse, the James Dyson Award-winning robot he designed to detect pipe leaks within two feet, or 0.6 metres. Now an MIT graduate, he’s pursuing the technology with his company, Watchtower Robotics.

The full range of Lighthouse prototypes | Photography Dyson

The Solution: A spelunking sputnik

It’s morning, and the birds are chirping in a San Antonio subdivision. Wu is standing outside, waiting for his team to arrive. The Texan city is the latest to get a trial run with Lighthouse; prior test sites include rural Virginia, Boston, Vienna and Coventry.

He’s been in San Antonio for two weeks, during which time the robot has been inserted into fire hydrants while the utility turns valves on and off to guide it under suburban streets. “It’s a floating device; it’s water-propelled. It’s made of rubber, so it’s pretty squishy and it can bend,” Wu explains. That helps it make hairpin turns underground and prevents it from getting stuck in pipes.

The device, which looks like a large badminton shuttlecock, has a blue skirt that acts as a suction sensor. It gets dropped into a fire hydrant and shimmies its way down into the pipe grid, the force of the water pushing it along on its data-collection journey.

Unlike other technologies that use satellite imaging or acoustic sensors to find cracks, Lighthouse’s sensors instead measure pressure drop. And whereas other technologies typically only pick up cracks once they’ve become real problems, Wu says Lighthouse can find fractures just four millimetres thick — ones that likely haven’t yet caused major infrastructure damage.

Dr Wu You with a prototype version of his invention | Photography Dyson

Lighthouse is also fast; a five-street inspection is expected to take less than two hours once all the equipment is ready to go. Local GPS units are placed on the street to help find Lighthouse underground. Once Lighthouse pops out of another hydrant, it’s ready to have its leak-detection and mapping data downloaded.

The San Antonio utility team seem to enjoy using the robot, says Wu. “They were pretty happy with the fact that it’s easy to use. I explained it to them briefly, and now they’re able to use it all by themselves. I just stand by and watch.”

That demonstrable ease of use and Lighthouse’s promised affordability have flooded Watchtower Robotics’ inbox with requests from at least 200 utilities and cities. The robot isn’t even commercially available yet, but Wu is hoping for an autumn launch date.

Lighthouse isn’t destined for the consumer market. It’s not particularly sleek-looking, and its intended purpose — saving cities time, money and water by finding pipe cracks — isn’t the sexiest topic. Most people will never even know that it could be flushing along through the pipes right underneath their feet. Yet, better leak-detection technology could discreetly, but dramatically, impact billions of lives as the spectre of water scarcity looms. At heart, Wu is motivated by this bigger picture.

“Once we get back to China, there are 1.5 billion people who need water,” he says. “You don’t want to shut down water for that many people every day.”

Words by Tracey Lindeman

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